Software performance depends on many things, most of the time not related to the sooftware itself. Coud you post additional information? Such has CPU, RAM and disk information? Also how much memory is available would be useful

Running a VM under Windows 7 is, in my experience, faster. VM's can be started via command-line scripts and be assigned static IP addresses. If this isn't an option, I would look at optimizing PostgreSQL, Python and Cherry Py (the OpenERP web server).

Compared to OERP v6.1 on the same hardware, the v7 is most definately slower. I often get errors because I click on a menu while the screen hasn't fully loaded yet. Or when typing in the searchbox, part of the text isn't captured correctly when typing. You have to type superslow for the searchbox to work.

If you're testing OpenERP on your own machine like me, try accessing it through "127.0.0.1:8069" instead of "localhost:8069".
This is much more responsive this way, don't got any real explanation for that (localhost name resolution should not be an issue)